A Short-Cycling Heater: What It Is and Why It’s Bad

As we head into the last stretch of winter, you’ll want to keep a close eye on your heating system. It’s done plenty of work already this winter, and now is a time when the stress on its components can catch up with it and cause it to malfunction or even breakdown entirely—and that’s never good, no matter how late in the season.

One particular issue to watch for is short-cycling. If your heating system is turning on and off multiple times over the hour, you may have a major repair problem on your hands that will require Fenton, MI heating system experts to fix.

What exactly is short-cycling?

A heater is said to be short-cycling when it becomes stuck in its start-up cycling and isn’t staying on long enough to complete the full cycle. A “cycle” is different for each type of heating system. For example, in an electric furnace, a cycle consists of the blower fan coming on, all of the heating elements turning on in a sequence and then turning off, and then the blower fan shutting off. When a heater short-cycles, it will stop and start multiple times during an hour.

Why is this a problem?

There are many reasons you don’t want a short-cycling heater in your home:

It puts an immense amount of stress on the heater’s components, nearly doubling the workload it does. It requires a great deal of energy to start the heating cycle, and if the heater is doing this twice as often as it should, it means a heater aging twice as fast. You can expect more repairs and a shorter system lifespan.

The extra work means higher gas and electrical bills.

Short-cycling makes it harder to properly heat the house. If the heater isn’t staying on long enough to have time to distribute heat to all the rooms, parts of the house won’t warm up.

Why is it happening?

The trickiest part about short-cycling is there’s no single cause for it. There are many reasons for a furnace or heat pump to get caught in the start-up cycle, ranging from minor annoyances to catastrophic problems.

The air filter for the HVAC system may be clogged. This causes less cool air to flow into the heater from the return vents, which can lead to the heater overheating and shutting down early. This is easy to fix: put in a fresh filter!

The thermostat is miscalibrated and reading incorrect temperatures. This will cause it to signal the heater to shut down before it needs to.

If you use a heat pump, the indoor coil may have frozen over. This restricts heat absorption and triggers problems like short-cycling.

The heater is incorrectly sized for the house. This is unlikely if you’ve noticed it late in the season, since a poorly sized heater should short-cycle from the moment it first starts to work. This is a hazard of having non-professionals install a heater, and the only option to fix the problem is to have a new heater—correctly sized by professionals—put in.

If you have a short-cycling heater and don’t know why it’s acting that way, call on our team.